﻿using System;
using System.Collections.Generic;

namespace Mello.ImageGallery.Extensions {
	public static class LongExtensions
	{
		private static readonly List<string> units = new List<string>(5) { "B", "KB", "MB", "GB", "TB" }; // Not going further. Anything beyond MB is probably overkill anyway.

		public static string ToFriendlySizeString(this long bytes)
		{
			var somethingMoreFriendly = TryForTheNextUnit(bytes, units[0]);
			var roundingPlaces = units[0] == somethingMoreFriendly.Item2 ? 0 : units.IndexOf(somethingMoreFriendly.Item2) - 1;
			return string.Format("{0} {1}", Math.Round(somethingMoreFriendly.Item1, roundingPlaces), somethingMoreFriendly.Item2);
		}

		private static Tuple<double, string> TryForTheNextUnit(double size, string unit)
		{
			var indexOfUnit = units.IndexOf(unit);

			if (size > 1024 && indexOfUnit < units.Count - 1)
			{
				size = size / 1024;
				unit = units[indexOfUnit + 1];
				return TryForTheNextUnit(size, unit);
			}

			return new Tuple<double, string>(size, unit);
		}
	}
}